Update:
Another weekend with not much time to do anything
I did get sick of cheap POS drills dying on me, so I went and bought this:
Relegating this hunk of cr*p to the bin:
I also scored some good drill bits off ebay cheap:
So I finally got around to test mounting a seat. Ignore all the pen marks and extra holes, I re-used some metal I already had for mounting these seats on R31 rails:
Mounted in car and with steering wheel:
Unfortunately, it seems like even with the rails adjusted all the way back, the seat is still a bit too far forward . I'm going to try another set that puts the seat further back compared to the rails, but I don't think I'll get more than an inch or so out of doing that. If that's not enough, I'll have to get more creative.